1. Field of the Invention
The present invention relates to a portable radio terminal device provided with both data communication and telephone functions.
2. Related Art Statement
Recently, various portable radio terminal devices are widely spread: portable radio telephones such as cellular phones and car phones, and portable data communication devices utilizing both portable radio telephone and computer devices. To maintain a good radio transmission between a portable radio terminal device and base stations, more and more transmission base stations are constructed and the antenna performance of the portable radio terminal device is maintained and improved.
However, the human body of the portable radio terminal device user has properties to scatter the radio frequency waves. For example, in case of a portable radio telephone device, holding of the portable radio telephone device in hand deteriorates the antenna gain by 5 dB and the contact of the antenna with the human head causes a gain deterioration of 10 dB. For this, in addition to the improvement of the antenna gain itself, the antenna is positioned so that it does not contact with the human head when the speaker of the portable radio telephone device is in contact with the human the human ear. Some portable radio telephone devices are provided with two types of antennas (a bar type antenna and a built-in antenna) and adopt the diversity antenna switching system so that the larger wave input to the antennas can be sent to the portable radio telephone device.
On the other hand, the portable radio telephone device is used for data communication in addition to the telephone application. Portable radio terminal devices incorporating a small computer to achieve both data communication and telephone functions are also becoming popular.
FIGS. 1A and 1B show the related art of the portable radio terminal device as described above. FIG. 1A is a front perspective view in which a portable radio terminal device is seen from the front and FIG. 1B is a back perspective view in which a portable radio terminal device with its case partially cut away is seen from the back.
The reference numeral 40 in the figure indicates a portable radio terminal device. The reference numeral 41 indicates a case having a shape of a thin rectangular parallelepiped, 42 indicates a data input/output section consisting of an LCD element and piezoelectric sensors, 43 indicates a speaker, 44 indicates a microphone, 45 indicates a bar antenna which extends and contracts flexibly, 46 indicates a plate type built-in antenna incorporated in the case 41, and 47 indicates a signal data circuit section, in which a circuit for processing radio signals and information data is mounted on a printed wiring board.
The data input/output section 42, the speaker 43, the microphone 44, the bar antenna 45 and the plate antenna 46 are respectively connected to the signal data circuit section 47. When the device is used for telephone service, the voice input from the microphone 44 is processed at the signal data circuit section 47 and then sent by radio transmission to base stations via the bar antenna 45 or the plate antenna 46. At the same time, the signal sent from base stations by radio transmission is received by the bar antenna 45 or plate antenna 46, processed at the signal data circuit section 47 and then output from the speaker 43. When the device is used for data communication, the data input from the data input/output section 42 is processed at the signal data circuit section 47, transmitted from the bar antenna 45 and/or plate antenna 46 to base stations. The device also receives the data transmitted from base stations, processes such data at the signal data circuit section 47 and then outputs or displays the data at the data input/output section 42. Note that the plate antenna 46 is the one most popularly used as the built-in antenna of portable telephones at present.
The portable radio terminal device 40 as described above has different spatial relations with the human body depending on its applications (whether it is used for radio telephoning or for data communication). FIGS. 2A to 2C show the utilization status of the portable radio terminal device 40 depending on the application.
FIG. 2A shows the radio telephone application, when the user holds the portable radio terminal device 40 in hand and applies the speaker 43 to the ear for talking over phone. FIG. 2B shows the data communication application, when the user holds an end of the case 41 of the portable radio terminal device 40 by one hand and inputs data or makes data communication operations with the input pointer on the data input/output section 42 by the other hand. FIG. 2C shows another status of the data communication application, when the user places the portable radio terminal device 40 on the desk and inputs data or makes data communication operations with the input pointer on the data input/output section 42 by one hand.
Though it is not shown, the user sometimes uses the portable radio terminal device 40 for data communication by placing it on the lap keeping the status shown in FIG. 2B so that the device is used not on the desk but on the user""s lap.
The portable radio terminal device 40 as described above has various utilization styles depending on the user both for radio telephoning and for data communication, and has diversified spatial relations with the human body. The area of contact between the portable radio terminal device 40 and the human body increases or decreases depending on the utilization style, and the influence caused by scattering of the radio frequency input to the bar antenna 45 and the plate antenna 46 also increases or decreases. As a result, even an antenna with optimum properties for a certain utilization style may have the characteristics largely deteriorated in other utilization styles.
Specifically, FIG. 3A shows the radio telephone application using the portable radio terminal device 40. In this case, the area from the speaker 43 to the section representing substantially a half of the data input/output section 42 on the surface of the portable radio terminal device 40 (shaded area 51a in the figure) is in contact with or is positioned very closely to the human head. In addition, as shown in FIG. 3B, the user holds the portable radio terminal device 40 from the back in either the right or left hand by gripping both its sides in order to position the device 40 near the human head. As a result, at least both sides of the portable radio terminal device 40 (shaded areas 51b and 51c in the figure) are in contact with the human body. Further, when the user holds the portable radio terminal device 40 tightly in hand, the palm comes into contact with the back of the device 40.
On the other hand, in the data communication application using a portable radio terminal device 40, supposing that the user is right-handed, the user generally grasps the head of the portable radio terminal device 40 with the bar antenna 45 and the speaker 43 by the left hand as shown in FIG. 4A and inputs data or makes data communication operations with the right hand using the data input pointer. In this case, the vertical face (shaded area 51d in the figure) of the portable radio terminal device 40 held by the left hand is in contact with the hand. In particular, when the bar antenna 45 of the portable radio terminal device 40 is entirely or partially covered with the left hand, the antenna characteristics are largely deteriorated by the left hand.
Besides, when the back of the portable radio terminal device 40 (the opposite side of the surface where the data input/output section 42, the speaker 43 and the microphone 44 are positioned) is placed directly on the desk, the portable radio terminal device 40 is closely in contact with the desk on its back (shaded area 5le in FIG. 4B). Many desks are recently made of metal with painted surfaces. If the top plate of the desk is metal, the desktop plate serves as a reflection plate of the radio wave and prevents the radio wave from sufficiently reaching the bar antenna 45 and the plate antenna 46 of the portable radio terminal device 40. In particular, this phenomenon may cause deterioration of the antenna gain at the plate antenna 46 in this case.
Considering the telephone function alone as the application of the portable radio terminal device 40, it is possible to minimize the antenna characteristics deterioration caused by the human body by arranging the bar antenna 45 and the plate antenna 46 of the portable radio terminal device 40 at positions so that they do not come into contact with or come close to the human body or the head in particular when the user holds the portable radio terminal device 40 in either the right or left hand for radio telephoning. However, with the addition of the data communication function to the applications of the portable radio terminal device 40 and diversification of utilization styles when the device is used for data communication, the antenna characteristics are susceptible to deterioration.
The portable radio terminal device having the radio telephone function and the data communication function is used in different ways depending on its application (whether it is used for radio telephoning or data communication). Due to the difference in the contact area between the human body and the portable radio terminal device, the antenna characteristics deterioration conditions under the influence of the human body to the radio frequency are diversified. Further, there are many ways of utilization for data communication using the portable radio terminal device. Corresponding to where the portable radio terminal device other than contact with the human body, the antenna characteristics deteriorate differently and the antenna characteristics vary depending on how the portable radio terminal device is used.
An object of the present invention is to provide a portable radio terminal device which can maintain stable antenna characteristics for both radio telephone application and data communication application.
Another object of the present invention is to provide a portable radio terminal device which can maintain stable antenna characteristics without being affected by the environment when the device is used for data communication.
A portable radio terminal device according to the present invention comprises a case having a shape of a thin rectangular parallelepiped and incorporating a radio transmission circuit, a data input/output means disposed on the surface of the case and connected to the radio transmission circuit, a microphone disposed at a longitudinal end of the surface, a speaker positioned at the other longitudinal end of the surface and in one of the longitudinal sections divided at the center of the latitudinal direction on the surface, and a linear antenna installed in the other longitudinal section divided at the center of the latitudinal direction on the surface which extends in the longitudinal direction of the case from inside of the case to outside via a side of the case adjacent to the end of the surface where the speaker is positioned.
A portable radio terminal device according to the present invention alternatively comprises a case having a shape of a thin rectangular parallelepiped and incorporating a radio transmission circuit, a data input/output section disposed on the surface of the case and connected to the radio transmission circuit, a microphone disposed at a longitudinal end of the surface, a speaker positioned at the other longitudinal end of the surface and in one of the longitudinal sections divided at the center of the latitudinal direction on the surface, a linear antenna installed in the other longitudinal section divided at the center of the latitudinal direction on the surface which extends in the longitudinal direction of the case from inside of the case to outside via a side of the case adjacent to the end of the surface where the speaker is positioned, and a built-in antenna disposed near the back in the case and connected to the radio transmission circuit.
A portable radio terminal device according to the present invention comprises a case having a shape of a thin rectangular parallelepiped and incorporating a radio transmission circuit, a data input/output means disposed on the surface of the case and connected to the radio transmission circuit, a microphone means disposed at a longitudinal end of the surface, a speaker means positioned at the other longitudinal end of the surface and in one of the longitudinal sections divided at the center of the latitudinal direction on the surface, and a linear antenna installed in the other longitudinal section divided at the center of the latitudinal direction on the surface which extends in the longitudinal direction of the case from inside of the case to outside via a side of the case adjacent to the end of the surface where the speaker means is positioned.
Other characteristics and profits of the present invention will be sufficiently clarified in the description below.